The Structure of DNA 1 CUT COLOR AND

The Structure of DNA 1

CUT, COLOR AND GLUE THE ILLUSTRATION OF THE DNA “DOUBLE HELIX” ONTO THE OUTPUT PAGE OF YOUR NOTEBOOK. DO THE FOLLOWING: 1. Label the components that make up the DNA. 2. Draw a box surrounding one nucleotide of the double helix and label this.

All life on earth uses a chemical called DNA to carry its genetic code or blueprint. In this lesson we be examining the structure of this unique molecule. By the way, can you make out what this is? 3

WHY DO WE STUDY DNA? DNA WHY IS IT IMPORTANT? We study DNA for many reasons, e. g. , its central importance to all life on Earth/ identifies organisms, How. Stuff. Works Videos "Solved: DNA Analysis" medical benefits such as cures for diseases or risks for genetic diseases http: //www. redorbit. com/news/video/science/5/d na_testing_for_everyone/25395/index. html 4

ESSENTIAL QUESTIONS: How is DNA similar to the Morse Code or any other secret codes? How can we tell if organisms are related to each other and how organisms change over time?

DNA? ? ? D=Deoxyribo N=Nucleic A=Acid Deoxyribonucleic Acid 6

WHAT IS DNA? DNA is often called the blueprint of life. In simple terms, DNA contains the instructions for making proteins within the cell. 7

CHROMOSOMES AND DNA? Our genes are on our chromosomes. Chromosomes are made up of a chemical called DNA. 8

THE SHAPE OF DNA? DNA is a very long polymer. The basic shape is like a twisted ladder or zipper. This is called a double helix. 9

THE DOUBLE HELIX MOLECULE The DNA double helix has two strands twisted together. 10

DNA DOUBLE HELIX “Steps of ladder” Nitrogenous Base (A, T, G or C) “Rails of ladder” Phosphate & Sugar Backbone

WHAT MAKES UP THE STRAND (RAILS) OF DNA? The backbone of the molecule is alternating phosphates and deoxyribose sugar phosphate deoxyribose bases 12

WHAT ARE THE FOUR NITROGENOUS BASES THAT MAKE UP THE STEPS OF THE LADDER? DNA has four different bases: Cytosine C Thymine T Adenine A Guanine G THESE MAKE UP THE STEPS OF THE LADDER!!! 13

nucleotide DNA is made up of repeating units called nucleotides 14

WHAT MAKES UP THE DNA NUCLEOTIDES? 1. Phosphate Group O O=P-O O 5 CH 2 O N 3. Nitrogenous base C 1 (A, G, C, or T) C 4 2. Sugar (deoxyribose) C 3 C 2

CUT AND GLUE THE NUCLEOTIDE ILLUSTRATION ONTO THE OUTPUT PAGE AND LABEL ITS THREE PARTS (PAY CLOSE ATTENTION TO THE ATTACHMENTS): A. Phosphate group B. Deoxyribose sugar B. C. Nitrogen base C.

CHARGAFF’S RULE: DNA has specific pairing between the nitrogen bases: Adenine must pair with Thymine Guanine must pair with Cytosine Their amounts in a given DNA molecule will be about the same T A G C

BASE-PAIRINGS H-bonds G C T A

TWO STRANDED DNA Remember, DNA has two strands that fit together something like a zipper. DNA was made of 2 long stands of nucleotides arranged in a specific way called the “Complementary Rule” 19

GENETIC DIVERSITY… Different arrangements of NUCLEOTIDES in a nucleic acid (DNA) provides the key to DIVERSITY among living organisms.

THE CODE OF LIFE… The “code” of the chromosome is the SPECIFIC ORDER that bases occur. A T C G T A T G C G G…

QUIZ 22

1. Which of the following bases pairs with adenine in DNA? a. Thymine b. Guanine c. Adenine d. Cytosine

WHAT IS THE DNA BASE PAIR RULE? 2. If the template of a strand of DNA is 5' AGATGCATC 3’ , the complementary strand will be — F 3' TCTACGTAG 5' CTACGTAGA 3' H 3' AGATGCATC 5' J 5' AGACGTCTA 3'

3. IN DNA, WHICH OF THE FOLLOWING DETERMINES THE TRAITS OF AN ORGANISM? F Amount of adenine G Number of sugars H Sequence of nitrogen bases J Strength of hydrogen bonds

4. A BIOLOGIST COLLECTS DNA SAMPLES FROM 2 SISTERS. THE YOUNGER SISTER HAS BLOND HAIR. THE OLDER SISTER HAS RED HAIR. THE SISTERS HAVE DIFFERENT TRAITS BECAUSE THEIR DNA CONTAINS DIFFERENT A. orders of nucleotides B. types of sugar molecules C. sized phosphate groups D. types of nitrogenous bases

5. IN ALL PLANTS AND ANIMAL CELLS, THE NUCLEUS CONTAINS LONG MOLECULES OF DNA. WHICH OF THE FOLLOWING BEST DESCRIBES THE FUNCTION OF DNA F. DNA provides the shape and structure of the nucleus. G. DNA packages materials for transport through the nucleus. H. DNA carries materials into and out of the nucleus. J. DNA contains the blueprint for producing the whole organism.

ASSIGNMENT Create a paper model of the double helix paying close attention to the components that make up the nucleotides!